How do I get my 1996 Nissan Sentra to start?

I have a 1996 Nissan Sentra GXE. It was running the other day, and I was able to start it yesterday (I didn’t drive it because it was dark and the speedometer wouldn’t light up). Today, no dice. I turn it over, and I get nothing. The radio plays, so obviously the battery is fine, but it doesn’t turn over, it doesn’t do anything. It just sits there, with the radio playing.My father suggested the starter, but I’ve no idea where it is or what it looks like. I’ve also found online that the inhibit relay could be the problem, but I’ve got no clue about that either. Help?